[Elastic stable intramedullary nailing in Ilizarov bone lengthening]

Bone lengthening with the Ilizarov technique gives good results but certain disadvantages are common: possible axial deviation during lengthening, long time to bone union, risk of fracture after removal of the external fixator. Associating the Ilizarov technique with elastic stable intramedullary nailing (ESIN) commonly used in traumatology has to be evaluated. We conducted an experimental study and report results of the first clinical application.

Eleven lengthenings of the tibia were conducted in dogs aged 1 to 4 years using an Ilizarov external fixator associated with ESIN. Lengthening started on day 1 and continued for 28 days. X-rays were obtained every week during lengthening, then at 15 and 30 days during the fixation period and 30 days after removal of the fixator. In two cases, arteriography was performed. In a pilot clinical trial, fourteen patients (8 males, 6 females) were treated with this method (1 humerus, 1 forearm, 7 femurs, 5 tibias). Mean patient age was 14 years.

In the experimental study, the x-rays showed rapid ossification of the regenerate which led to increased tibia length in 7 cases from 1.25 to 2 mm/day. Total bone union was observed in four dogs during the lengthening period. At day 15 of the fixation period, all tibia had fused with a good quality cortical bone and healing of the growth part of the regenerate. In three dogs, the external fixator was removed at day 15 of fixation and weight-bearing was total with the ESIN in place. No axial deviation and no skin problems were observed. The medullary artery was seen on the two arteriograms. In the clinical trial, bone union of the regenerate appeared earlier than in the Ilizarov series. The regenerate always displayed good density on the x-rays, proving intense bone activity. In three patients, the lengthening rate was increased to avoid premature bone fusion. The endosteal bone regenerate was obvious. Mean healing index was 18.6 days/cm (SD=6.2). Weight-bearing was allowed at six weeks. The desired correction was achieved in all patients and no complications were related to ESIN.

Bone lengthening may be obtained with an intramedullary locking nail which avoids the use of an external fixator but also destroys the endomedullary circulation. Our experimental and clinical study shows that use of an ESIN does not inhibit the endosteal regenerate and seems to improve new bone formation. In many patients, the lengthening rate had to be increased to avoid premature bone fusion. When used in optimal conditions, ESIN can stimulate new endosteal and periosteal bone formation. In addition, ESIN increases shaft stability avoiding the risk of axial deviation. ESIN plays an additional role of stabilization after early removal of the external fixation.